Adrenoleukodystrophy (/-ˌlu-koʊ-ˈdis-trə-fiː/; also known as X-linked adrenoleukodystrophy, ALD, X-ALD, adrenomyeloneuropathy, AMN, Siemerling–Creutzfeldt disease or bronze Schilder disease) is a disease that is linked on the X chromosome. It is a result of fatty acid digestive enzymes not breaking up the fats. These fats build up in the brain. They damage the myelin that surrounds nerves. This can cause seizures and hyperactivity. It can also cause problems with speaking, listening and understanding verbal instructions.